The present invention generally relates to a machine for production of mineral wool from a mineral melt, and the invention more specifically relates to a device for the machine designed to remove solidified mineral material, termed flash, which forms on a channel, from which a mineral melt is discharged into a fiber producing unit.
When mineral wool is produced, a continuous flow of the mineral melt is led from a melt channel to a fiber-producing device in the form of a freely falling melt jet. The fiber-producing device is e.g. a spinning machine or a simple blow-off nozzle. Most fiber-producing devices require, in order to function satisfactorily and produce mineral wool having a satisfactory quality, that the melt is fed to the fiber-producing elements in a controllable way. Partly the flow variations must not be too large and partly every melt jet must hit the fiber-producing device in a certain area, if the fiber production is to take place in an optimal way.
Generally the mineral melt is led to the fiber-producing device in a V-shaped channel. The channel is terminated with a spout, designed in a suitable way, and it is positioned in such a way, that the melt jet hits the fiber-producing device in the proper area.
In case the channel is not completely heat-insulated, it will cool the mineral melt, particularly alongside the bottom of the channel mineral. When wool is produced the temperature of the melt is close to the melting point of the mineral and therefore any slight amount of cooling alongside the bottom of the channel may cause the melt to approach its solidification temperature resulting in the viscosity of the melt increasing.
When this viscous melt reaches the spout and leaves the channel, it will be additionally cooled by the ambient air and solidify. As solidification takes place, the flash is formed slowly, to a greater or lesser degree, roughly in the same way as when icicles are formed. This solidification process is referred to as flash formation and when a viscous melt is close to a temperature where solidification can occur, the melt is said to have flash formation tendencies.
In case the conditions favor a flash-formation, then the flash usually grows successively. Consequently, the melt jet, which normally falls freely from the spout of the melt channel, will flow on the flash and then the melt jet may have its course changed in an unpredictable way. This problem has been solved earlier by removing the flash manually by means of a hook or a scraper.
Manual removal of flash requires the presence of personnel in order to check whether a flash has been formed and if that is the case to remove the flash. Also, strength as well as a certain degree of skill are required in order to remove the flash, particularly since, when the flash is scraped off, melt to some extent comes along. Care must be taken to assure that scraped off melt does not splash and injure personnel or damage surrounding equipment. Also, the removal of the flash can result in disturbances of the fiber production process.
Thus, the purpose of the present invention is to solve the above-mentioned problems and suggest a device designed to, mechanically and without risks of harming personnel and the plant, remove flash from the melt channel in a fiber-producing plant in connection with the fiber production. According to the invention said device comprises a rod or a finger, made of a heat resistant material, e.g. steel, which finger is disposed and designed in such a way that it can be quickly moved mainly horizontally past the channel, vertically below the spout of the channel.
This movement is done mechanically and is identical over and over again, which means that the rest of the parts of the plant can be designed to accommodate this removal. For example, a collection device for the removed flash may be provided or no sensitive plant parts will be located in the direction in which the flash will be propelled as it is scraped off.
The flash removal can also be remote-controlled, e.g. from a control room, in which the operator is protected from that noise, heat and melt splash, which usually is generated, where a mineral melt is transformed into fibers.
Also the invention results in a quick removal of the flash.
Thus, we have found that it is advantageous to move the flash removal device mainly perpendicular to the longitudinal direction of the melt channel, e.g. from a rest position on one side of the melt jet to a corresponding rest position on the other side. This process is different from the manual flash removal, which usually is done by movements in the longitudinal direction of the melt channel, normally in a direction towards the operator.
It is particularly advantageous to mount the flash removal finger around a vertical shaft on the lower surface of the melt channel, preferably in the center line of the channel, and to rotatably mount the flash removal finger allowing it to swing in a movement past and through the melt jet and through any flash material that may have formed. This movement suitably can be done by means of a compressed-air piston or another motor, which swings or rotates the flash removal finger and makes it scrape off the flash material from the melt channel. When the finger is designed with a swinging movement, the flash is scraped off in one direction and alternately in the other direction. This means that a collection device for the flash material must be used on both sides of the melt jet. The flash removal finger can alternatively be designed to revolve completely around its shaft, i.e. from a rest position past the flash and back to the same rest position. Then the flash material always is scraped off in the same direction, and one single collection device for the flash material is sufficient.